/*
GanttProject is an opensource project management tool.
Copyright (C) 2010 Dmitry Barashev

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 3
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/
package net.sourceforge.ganttproject.calendar.walker;

import java.util.Date;

import net.sourceforge.ganttproject.calendar.GPCalendar;
import net.sourceforge.ganttproject.time.TimeUnit;

/**
 * Abstract iterator-like class for walking forward over the calendar timeline
 * doing steps of the specified size. It takes into account calendar working and
 * non-working time.
 *
 * @author dbarashev (Dmitry Barashev)
 */
public abstract class ForwardTimeWalker {
    private final GPCalendar myCalendar;
    private final TimeUnit myTimeUnit;

    protected ForwardTimeWalker(GPCalendar calendar, TimeUnit timeUnit) {
        myCalendar = calendar;
        myTimeUnit = timeUnit;
    }

    protected TimeUnit getTimeUnit() {
        return myTimeUnit;
    }
    abstract protected boolean isMoving();

    public void walk(Date startDate) {
        Date unitStart = myTimeUnit.adjustLeft(startDate);
        while (isMoving()) {
            boolean isWeekendState = myCalendar.isNonWorkingDay(unitStart);
            if (isWeekendState) {
                Date workingUnitStart = myCalendar.findClosestWorkingTime(unitStart);
                assert workingUnitStart.after(unitStart);
                processNonWorkingTime(unitStart, workingUnitStart);
                unitStart = workingUnitStart;
                continue;
            } else {
                Date nextUnitStart = myTimeUnit.adjustRight(unitStart);
                processWorkingTime(unitStart, nextUnitStart);
                unitStart = nextUnitStart;
            }
        }
    }
    protected abstract void processWorkingTime(Date intervalStart, Date nextIntervalStart);

    protected abstract void processNonWorkingTime(Date intervalStart, Date workingIntervalStart);
}
